"On two occasions I have been asked,—"Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?" I am not able rightly to apprehend the kind of confusion of ideas that could provoke such a question."
- Charles Babbage

To clarify, they're not countdown timers (any more, a long time ago they were), they're deadlines. So as soon as the site comes back up, if it sees a deadline that passed in the interim the server will immediately finish that action.